Motor vehicle clutch controlled differential units and systems and methods for their operation are known for example from EP 2 116 411 A1 or DE 40 39 391 A1. Here, two control valves which are separately activatable are used in each case to specifically activate the first and second clutch respectively with a certain control pressure in order to influence the clutch moment to be transmitted from the respective clutch to the associated drive wheel as a function of the driving state. These configurations make it possible to apply different torques to the right and left drive unit and in approximately any conceivable driving situation adjust the desired power or moment distribution over the two drive wheels of an axle and specifically intervene in a correcting manner in critical driving situations.
Disadvantageous in the systems and methods mentioned above however is their complexity. They require hardware and software which are complex and potentially prone to malfunctioning, and a multitude of components. The development and application expenditure in the case of a vehicle is high. If, furthermore, it is taken into account that such systems and methods are generally provided as all-wheel modules for vehicles with all-wheel drive that can be switched off or added on and the actual driving proportion in all-wheel drive mode during the lifespan of a vehicle is typically very low, the expenditure for the development and application of such a system and method is not infrequently considered too high and too expensive by the manufacturers. This applies in particular to manufacturers of vehicles below the premium segment and of vehicle types which, because of their intended purpose, do not have any particular need for such systems as can be the case for example with off-road vehicles.
Furthermore, systems and methods for activating a gearless, clutch-controlled differential unit of a motor vehicle are known or in development, in the case of which the two clutch sides are each always supplied with the same value of a control variable responsible for the respective clutch moment. However, such systems have the disadvantage that the one drive wheel can no longer be assigned a transmittable drive moment which differs from the transmittable drive moment assigned to the other drive wheel. The specific adjusting of a yaw moment for influencing the active yaw function or a slip that is adjustable individually for each side is no longer possible. With such systems, which are described in the international Patent Application PCT/EP2013/077248 or the German Disclosure Publication DE 40 21 747 A1, a substantial advantage is therefore forfeited which gearless, clutch-controlled differential units with individually activatable clutches offer in principle.